When looking at devices, you need to know what file types they support. Here are common file types for ebooks, audiobooks and music.
| format | type | Used by |
| aac | audio | iTunes |
| mp3 | audio | Freegal, many ereaders, mp3 players |
| wma | audio | Windows Media Audio |
| azw | ebook | Kindle |
| mobi | ebook | Kindle, free ebooks |
| ePub | ebook | Most ereaders (not Kindle), Overdrive, free ebooks |
|
ebook/document |
Overdrive, most ereaders, free ebooks | |
| TXT | raw text ebook/document | free ebooks, most ereaders |
